Search Publications
Tracing the Propagation of Shocks in the Equatorial Ring of SN 1987A over Decades with the Hubble Space Telescope
Fransson, Claes; Larsson, Josefin; Tegkelidis, Christos
The nearby SN 1987A offers a unique opportunity to investigate the complex shock interaction between the ejecta and circumstellar medium. We track the evolution of the optical hot spots within the equatorial ring (ER) by analyzing 33 Hubble Space Telescope imaging observations between 1994 and 2022. By fitting the ER with an elliptical model, we d…
Witt's Hyperbola Is Both Predicted and Observed to Pass Close to the Lensing Galaxies in Quadruple Quasars
Schechter, Paul L.; Luhtaru, Richard
When a rectangular hyperbola is constructed from the image positions of a quadruply lensed quasar, as proposed by Witt, it passes very close to the lensing galaxy. The median measured perpendicular offset between the observed light center of the lens and Witt's hyperbola is 0.″013 for a sample for 39 systems lensed by a relatively isolated galaxy.…
Deriving the Interaction Point between a Coronal Mass Ejection and High-speed Stream: A Case Study
Dumbović, Mateja; Temmer, Manuela; Remeshan, Akshay Kumar
We analyze the interaction between an interplanetary coronal mass ejection (ICME) detected in situ at the L1 Lagrange point on 2016 October 12 with a trailing high-speed stream (HSS). We aim to estimate the region in the interplanetary (IP) space where the interaction happened/started using a combined observational-modeling approach. We use minimu…
The Black Hole Mass and Photometric Components of NGC 4826
Gebhardt, Karl; Kormendy, John; Lauer, Tod R. +6 more
We present infrared photometry and Hubble Space Telescope imaging and spectroscopy of the Sab galaxy NGC 4826. Schwarzschild dynamical modeling is used to measure its central black hole mass M. Photometric decomposition is used to enable a comparison of M to published scaling relations between black hole masses and properties of host bulges. This …
The Formation of Filaments and Dense Cores in the Cocoon Nebula (IC 5146)
Kwon, Woojin; Cho, Jungyeon; Chung, Eun Jung +4 more
We present 850 µm linear polarization and C18O (3 ‑ 2) and 13CO (3 ‑ 2) molecular line observations toward the filaments (F13 and F13S) in the Cocoon Nebula (IC 5146) using the JCMT POL-2 and Heterodyne Array Receiver Program instruments. F13 and F13S are found to be thermally supercritical with identified dense cores a…
An Outbursting Protostar: The Environment of L1251 VLA 6
Ábrahám, Péter; Kóspál, Ágnes; Kun, Mária +6 more
Young protostars that undergo episodic accretion can provide insight into the impact on their circumstellar environments while matter is accreted from the disk onto the protostar. IRAS 22343+7501 is a four-component protostar system with one of those being a fading outbursting protostar, which was obseved with the Karl G. Jansky Very Large Array (…
2019 UO14: A Transient Trojan of Saturn
Tholen, David J.; Weryk, Robert; Hui, Man-To +5 more
Saturn has long been the only giant planet in our solar system without any known Trojan members. In this Letter, with serendipitous archival observations and refined orbit determination, we report that 2019 UO14 is a Trojan of the gas giant. However, the object is only a transient Trojan currently librating around the leading Lagrange p…
Astrometric Jitter as a Detection Diagnostic for Recoiling and Slingshot Supermassive Black Hole Candidates
Natarajan, Priyamvada; Gezari, Suvi; Ward, Charlotte +4 more
Supermassive black holes (SMBHs) can be ejected from their galactic centers due to gravitational wave recoil or the slingshot mechanism following a galaxy merger. If an ejected SMBH retains its inner accretion disk, it may be visible as an off-nuclear active galactic nucleus (AGN). At present, only a handful of offset AGNs that are recoil or sling…
A Multiwavelength Study of the Symbiotic Mira HM Sge with SOFIA and HST
Goldman, Steven R.; Montiel, Edward; Sankrit, Ravi +3 more
We have targeted the dusty symbiotic Mira system HM Sge with four instruments from the IR to the UV. We have used these observations along with archival observations to study how the system has been evolving after its 1975 nova-like outburst. We have detected rovibrational water emission in a symbiotic system for the first time using new EXES high…
Spectro-temporal Evolution of 4U 1702-429 Using AstroSat-NICER
Misra, Ranjeev; Chattopadhyay, Suchismito; Mandal, Soma +2 more
We present the broadband spectral and timing properties of the atoll source 4U 1702-429 using two observations of AstroSat with the second one having simultaneous NICER data. For both observations, the spectra can be represented by a Comptonizing medium with a blackbody seed photon source that can be identified with the surface of the neutron star…